Abstract
Four proteins with MW of 58,000 can be separated as a linear array by 2-dimensional gel electrophoresis. They are highly concentrated in the goldfish optic nerve and are designated as ON1, ON2, ON3 and ON4. Proteins ON1 and ON2 are undetectable in the optic nerve after disconnection and their concentration is gradually restored during regeneration. In vitro incubations of retinas, optic nerves or tecta in the presence of [35S]methionine indicate that proteins ON1 and ON2 are of retinal origin. The labeling rate of these proteins in the retina increases 4-fold after optic nerve crush whereas the overall labeling rate in the retina remains largely constant. Their synthesis cannot be detected in tissues devoid of retinal ganglion cells. This is consistent with the view that ON1 and ON2 are synthesized by retinal ganglion cells and are consequently of neuronal origin in the optic nerve. Similar experiments indicate that ON3 and ON4 are of nonneuronal origin. They are synthesized in the optic nerve in the absence of retinal ganglion cells.